This is the third season Major League Soccer has operated under a FIFA-mandated transfer window and still confusion persists.

The domestic window opened Aug. 15 and will close Sept. 15. The European window is open until the end of the month and moves can be made until then. Many outlets reporting transfer deals have confused these dates as the flurry of transfers in Europe continues unabated.

Under FIFA directives, each national association is limited to two transfer windows per year, during which contracted professional players may be registered. In cases involving a player changing countries, and thus the jurisdictions of separate national associations, his status depends on the league or country to which he is moving, not the one he is leaving.

Most European associations adhere to the standard transfer window. FIFA has allowed clubs to loan players to other clubs in the same country outside of the transfer windows, but otherwise, loans are treated the same as transfers. A player can only make two such moves within a 12-month period.

So if Red Bull Salzburg wants to loan or sell Markus Schopp to Red Bull New York, as is being discussed, the deal would have to be completed and he would need to be registered prior to Sept. 15. It might take additional time for him to secure a work visa as well. If he is loaned to MLS, he would also have to wait until Jan. 1, when the European window re-opens, to register and be eligible to play in Europe.

Out of contract players are not subject to these restrictions, except if a player wasn't released while the transfer window is open, he cannot be registered until it re-opens.

MLS chose the summer dates it did to possibly snap up European-based players unable to secure a transfer prior to the closing of the European window, leaving the league two weeks to sign them. But in the case of loans, the disparity between the European and MLS transfer windows complicates player movement, since the respective seasons end while the transfer windows at the other end are closed.

A player going on loan from MLS to Europe at the end of the MLS season thus could be registered in Europe no earlier than Jan. 1. To play in MLS he would have to return prior to the closing of the major domestic window March 30, or wait until Aug. 15 to play in the league.

These restrictions were to blame, in part, for the collapse of loan deals that would have sent Landon Donovan and Carlos Ruiz to Europe two years ago. FIFA also doesn't permit players to be registered with two different clubs at the same time, partially in response to the case of Jorge Campos traveling back and forth between clubs in the U.S. and Mexico during his MLS stint.

BLACKMUN LEAVES AEG. Chief operating officer Scott Blackburn, who joined AEG four years ago, has resigned.

Blackmun, who was interim president of the U.S. Olympic Committee prior to joining AEG, handled some of AEG's soccer operations, including the futile search for a stadium option in San Jose and the eventual move of the Earthquakes to Houston.

AEG Sports President Shawn Hunter, who was promoted to that position last September, oversees the sports companies and properties operated by AEG.